Cargando…
Voltage-sensitive potassium channels in Limulus ventral photoreceptors
The steady-state slope conductance of Limulus ventral photoreceptors increases markedly when the membrane is depolarized from rest. The ionic basis of this rectification has been examined with a voltage- clamp technique. Tail currents that occur when membrane potential is repolarized after having be...
Formato: | Texto |
---|---|
Lenguaje: | English |
Publicado: |
The Rockefeller University Press
1978
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2215097/ https://www.ncbi.nlm.nih.gov/pubmed/621492 |
_version_ | 1782148991158321152 |
---|---|
collection | PubMed |
description | The steady-state slope conductance of Limulus ventral photoreceptors increases markedly when the membrane is depolarized from rest. The ionic basis of this rectification has been examined with a voltage- clamp technique. Tail currents that occur when membrane potential is repolarized after having been depolarized have been identified. The tail currents reverse direction at a voltage that becomes more positive when Ko is increased. Rectification is reduced by extracellular 4- aminopyridine and by intracellular injection of tetra-ethyl-ammonium (TEA). These results indicate that the membrane rectification around resting potential is due primarily to voltage-sensitive K+ channels. The increase in gK caused by depolarization is not mediated by a voltage-dependent rise in in Cai++, since intracellular injection of Ca++ causes a decrease rather than an increase in slope conductance. TEA can be used to examine the functional role of the K+ channels because it blocks them without substantially affecting the light- activated Na+ conductance. The effect of TEA on response-intensity curves shows that the K+ channels serve to compress the voltage range of receptor potentials. |
format | Text |
id | pubmed-2215097 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1978 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-22150972008-04-23 Voltage-sensitive potassium channels in Limulus ventral photoreceptors J Gen Physiol Articles The steady-state slope conductance of Limulus ventral photoreceptors increases markedly when the membrane is depolarized from rest. The ionic basis of this rectification has been examined with a voltage- clamp technique. Tail currents that occur when membrane potential is repolarized after having been depolarized have been identified. The tail currents reverse direction at a voltage that becomes more positive when Ko is increased. Rectification is reduced by extracellular 4- aminopyridine and by intracellular injection of tetra-ethyl-ammonium (TEA). These results indicate that the membrane rectification around resting potential is due primarily to voltage-sensitive K+ channels. The increase in gK caused by depolarization is not mediated by a voltage-dependent rise in in Cai++, since intracellular injection of Ca++ causes a decrease rather than an increase in slope conductance. TEA can be used to examine the functional role of the K+ channels because it blocks them without substantially affecting the light- activated Na+ conductance. The effect of TEA on response-intensity curves shows that the K+ channels serve to compress the voltage range of receptor potentials. The Rockefeller University Press 1978-01-01 /pmc/articles/PMC2215097/ /pubmed/621492 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/). |
spellingShingle | Articles Voltage-sensitive potassium channels in Limulus ventral photoreceptors |
title | Voltage-sensitive potassium channels in Limulus ventral photoreceptors |
title_full | Voltage-sensitive potassium channels in Limulus ventral photoreceptors |
title_fullStr | Voltage-sensitive potassium channels in Limulus ventral photoreceptors |
title_full_unstemmed | Voltage-sensitive potassium channels in Limulus ventral photoreceptors |
title_short | Voltage-sensitive potassium channels in Limulus ventral photoreceptors |
title_sort | voltage-sensitive potassium channels in limulus ventral photoreceptors |
topic | Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2215097/ https://www.ncbi.nlm.nih.gov/pubmed/621492 |